Bohl Pir (Pier) (born 1865, Walk (now - Valka), Latvia – died 1921, Riga) – mathematician.

Pir Bohl received his early education in Valka and then attended a German school in Viljandi (Estonia). In 1884, he entered the Faculty of Physics and Mathematics at the University of Dorpat (now Tartu), graduating in 1887 with a gold medal for his essay “Theory of Linear Invariants of Linear Differential Equations.”

In 1893, Bohl was awarded the degree of Master of Mathematics for his pioneering research into quasiperiodic functions, becoming the first scholar to study them. His ideas gained broader recognition a decade later when the French astronomer E. Esclangon independently discovered the same functions and named them “quasiperiodic.” Bohl’s concepts were subsequently developed further by the mathematician Harald Bohr.

Bohl taught in schools and at teacher training colleges, and from 1895, he was a lecturer at the Riga Polytechnic Institute, where he later headed the department. In 1900, he earned his doctoral degree from the University of Dorpat and was appointed professor at the Riga Polytechnic Institute. His doctoral thesis introduced a novel approach to the application of topological methods in the study of first-order differential equation systems. He formulated and proved several theorems and contributed to the development of functional theory and the theory of ordinary differential equations.

He was also an active chess player on the Latvian national team and made a notable contribution known as the “Riga Variation of the Spanish Opening.” In 1914, during the First World War, the Riga Polytechnic Institute was evacuated to Moscow. In 1919, Bohl returned to newly independent Latvia and assumed the chair of mathematics at the University of Latvia. He authored a textbook on higher mathematics, covering analytic geometry and mathematical analysis, which was used for the next twenty years.

He is regarded as the most prominent Latvian mathematician of the first half of the 20th century.

Selected Work:

Über die Bewegung eines mechanischen Systems in der Nähe einer Gleichgewichtslage J. für reine und angewandte Mathematik, Vol. 127, No. 3, 1904.